spanner-reference

A reference repo for using sqlalchemy-spanner and alembic with the spanner emulator. This repository is focused on local development.

Before doing anything else, run poetry install.

Running locally against Spanner emulator

1. Install and start the Spanner emulator. gcloud emulators spanner start. Note that emulator data DOES NOT persist between sessions. Make sure to follow the directions for creating a gcloud config for the emulator specifically.
2. Set environment variables for emulator

export SPANNER_EMULATOR_HOST=localhost:9010
export DB_URI=spanner+spanner:///projects/emulator-test-project/instances/test-instance/databases/test-db

4. Create a Spanner instance and db in the emulator: poetry run python scripts/create_db.py

Running against deployed instance

1. Set environment variable DB_URI to a deployed empty Spanner DB (no tables). Use the default gcloud config, NOT the emulator config: gcloud config configurations activate default.

export DB_URI=spanner+spanner:///projects/my-project-id/instances/spanner-demo/databases/alembic_test

Alembic migrations

• poetry run alembic revision --autogenerate -m init to generate a migration
• poetry run alembic upgrade head to upgrade to latest

References

• https://github.com/googleapis/google-cloud-python/tree/main/packages/sqlalchemy-spanner
• https://docs.cloud.google.com/spanner/docs/emulator